In obtaining a biopsy of a patient's esophageal or other tract organ tissues via an end-viewing endoscope, the distal end of the scope must be turned to the side to aim the instrument in the direction of the tissues to be sampled in order to correctly direct a biopsy needle or forceps as such instrument emerges from the distal end opening of the instrument lumen of the endoscope. In addition, the conical field of view provided by the endoscope's optical element is generally on the order of about 90.degree., centered along the axis of the scope's distal end portion. This procedure is frequently difficult, however, owing to the narrowness of the esophagus. Although a side-viewing endoscope can be used to obtain an esophageal biopsy, the scope is nearly useless in examining the stomach, thus often necessitating use of both an end-viewing endoscope and a side-viewing endoscope during the same surgical procedure. Accordingly, a need exists for a device to facilitate the obtaining of an esophageal or other narrow tract organ biopsy via an end-viewing endoscope.
Some endoscopes include two separate biopsy channels for the simultaneous insertion of multiple endoscopic instruments. In addition, U.S. Pat. Nos. 5,025,778 and 4,646,722 to Silverstein et al. disclose the application, to endoscope insertion members, of removable sheaths having expandable biopsy channels. Such endoscope sheaths enable any existing endoscope to be retrofitted to have multiple biopsy channels. Such multiple biopsy channels, however, cannot be used to their full potential, without the existence of flexible endoscopic instruments with distal end portions which can be turned or directed by an operator at the proximal ends of the instruments. One solution is to provide each endoscopic instrument with its own set of orientation control cables. Although this solution is certainly feasible, a less expensive solution would be beneficial.
Another proposed solution is disclosed in U.S. Pat. No. 5,386,818, which discloses an endoscopic instrument comprising an endoscope insertion tube provided with a biopsy channel and an elongate tubular member inserted into the biopsy channel, the tubular member being provided with a distal end portion having a spring bias tending to form the distal end portion into an arcuate configuration. The tubular member is longitudinally slidable in the biopsy channel, whereby the distal end portion may be alternately maintained in a relatively straightened configuration in a distal end of the biopsy channel and moved outside of the biopsy channel to assume the arcuate configuration. An elongate flexible endoscopic instrument is slidably inserted into the tubular member so that an operative tip at a distal end of the instrument may project outwardly from the distal end portion upon an ejection of at least a part of the distal end portion of the tubular member from the biopsy channel. Such apparatus suffers from a number of disadvantages, however, due to the limited field of vision at the distal end of the scope. Because the spring-biased portion of the tubular member starts to bend as soon as it is extended beyond the tip of the endoscope, the end of the tubular member quickly directs the instrument to a location potentially outside the operator's field of view. Upon further movement of the tubular member distally of the scope's tip, the tubular member turns back on itself, directing the instrument to a position proximal to scope tip and completely out of view of the operator. Thus, while the instrument disclosed in U.S. Pat. No. 5,386,818 may be satisfactory for some procedures, a surgical instrument which remains in the operator's field of view when directed perpendicular to the scope's axis would be particularly advantageous.